I've seen quite a few reviews of MREs (meal, ready to eat) from around the world, and was fed by a couple Canadian Forces bases when I was in Air Cadets, and based on that, I'd say military food is generally pretty good these days. But yeah, bitching about the food in the military is an old trope so I've never heard anyone trying to sell food by calling it military grade.

The only food you could probably sell that way would be something like an energy bar. And there are energy bars out there that could accurately be described as military grade, since they're an item that is sometimes included in MRE's.